Systems and methods for modular construction of large structures

ABSTRACT

Systems and methods wherein large superstructures are simplified and then constructed using prefabricated, modular components. The components include a combined prefabricated primary support and roof system and shop-fabricated floor panels.

CROSS-REFERENCES TO RELATED APPLICATIONS

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems and methods for a simplifiedframing system that facilitates cost-efficient, modular construction oflarge structures, and more particularly, to systems and methods forerecting large power generation plant structures.

2. Description of the Prior Art

Large structures such as, for example, power generation plants,petro-chemical facilities, mining and metal structures, industrialbuildings, etc. are common. Many of these structures are now being builtglobally, especially in remote locations. Companies that obtaincontracts for building such structures obviously want to minimize effortand expenses. Adding to the cost presumed, there often are timeconstraints involved in erecting structures. As steel erection istypically on the “critical path” of a project schedule, the requiredsteel erection duration directly impacts the overall project schedule.

A common method for erecting such structures is a “stick-built”approach, where conventional columns, beams, girders, vertical braces,horizontal braces, deck, studs, grating pieces and others are assembledat the site. Consequently, this involves a large amount of labor.Additionally, tracking of the large number of members can be expensiveand time-consuming.

A second method involves prefabrication of large-scale,three-dimensional modules. However, such modules are typically much morecostly, due to special shipping requirements and the inevitable wastedspace on the vehicles being used for the shipment.

Thus, improved systems and methods for cost-effectively and efficientlydesigning, fabricating and erecting large structures is needed.

SUMMARY OF THE INVENTION

Broadly, the present invention provides systems and methods whereinconstruction of structures is grossly simplified through the use ofprefabricated, modular components fabricated to a maximum size thatstill may be stacked and then shipped conventionally on trucks. Thecomponents are erected to provide a simplified “super-frame,” whichcomprises a combined prefabricated primary support and roof system;shop-fabricated composite columns; and shop-fabricated floor panels thatare assembled into bays within the primary support frame.

More particularly, the present invention provides a method of erecting astructure for generating power with a boiler, where the method compriseserecting a primary “super-frame” of only approximately 650-750 pieces,preferably only approximately 700 pieces. Components of the“super-frame” include combined boiler support/roof truss sections, largecomposite columns built-up from available shapes, deep horizontaltrusses that consist of lacing adjacent floor beams and large floorpanels (i.e., up to 12 feet×60 feet and including shop welded grating,checker plate or composite decking) that bear on column line members.The simplified “super-frame” greatly mitigates the required erectionduration prior to commencement of the boiler.

In accordance with one aspect of the present invention, a majority ofcomponent connections are accomplished using bearing connections. Whileconventional steel structures involve members framing into one another,and thus lead to bolting and “fit-up” issues, all floor panels for thisstructure simply set on previously erected steel, with “stops” designedto prevent movement.

In accordance with another aspect of the present invention, the primarysupport is for a boiler for generating power and the support comprisesusing a common structure for both boiler support and roof framing.

In accordance with a further aspect of the present invention, nodiagonal horizontal bracing is used. In adddition, no vertical bracingis used in one framing direction.

In accordance with yet another aspect of the present invention,components are sized to fit on a standard truck-trailer.

According to another aspect of the present invention, grating is usedintegrally with framing to create a horizontal diaphragm.

The following detailed description together with the accompanyingdrawings will provide a better understanding of the nature andadvantages of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a superstructure constructed withprefabricated components in accordance with the present invention;

FIG. 2 is perspective view of a combined primary/roof support structure;

FIG. 3 is a perspective view of a shop prefabricated panel for grating;

FIG. 4 is a perspective view of a shop prefabricated panel for checkerplates;

FIG. 5 is a top perspective view of a shop-fabricated composite panel;

FIG. 6 is a perspective bottom view of the shop-fabricated floor panelillustrated in FIG. 5; and

FIG. 7 is an illustration of a bearing-type connection.

DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

The present invention provides systems and methods for erecting largestructures or “superstructures” through the use of prefabricated modularcomponents. While the present invention will be described with referenceto a power-generating plant, those skilled in the art will understandthat the present invention may be used for other large structures suchas, for example, petro-chemical facilities, mining and metalsfacilities, industrial buildings, etc.

With reference to FIG. 1, a boiler building volume 9 may be viewed asthree discrete sections. Specifically, a combined boiler and roofsupport system 10 at the top of the structure is one primary section.The second discrete section comprises soot blower floors in the form ofbays made up of prefabricated panels for grating 11, checker plates 12,and floor panels 13. Lower levels, also in the form of bays and made upof panels 11, 12 and 13, are a third discrete section and support coalconduits, large ductwork ash conveyors, and miscellaneous commoditysupports.

To reduce the amount of time to assemble such a structure, the first twodiscrete sections may be assembled simultaneously. Generally, as anexample for this type of power generating plant, only approximately 700primary structural members are used. These members include buildingcolumns and column line members, boiler support systems, includingtrusses, stair tower modules, and soot blower floor grating panels andboiler front checker plate burner panels placed adjacent the boilercavity. Preferably, these modules include 60-foot super columns.

The lower levels may be installed and assembled subsequent to assemblyof the first two sections since it can be done at the same time as theprimary boiler structure erection.

As may be seen in FIG. 1, preferably the bottom level of the structureincludes bays 18 wherein trucks may drive for unloading of fuel andother supplies.

Combined primary (in this case, boiler)/roof support structure 10 isillustrated in FIG. 2. Shop prefabricated panels for grating 11 andchecker plates 12 are illustrated in FIGS. 3 and 4, respectively.Shop-fabricated composite panels 13 are illustrated in FIGS. 5 and 6.

The combined boiler roof system is sloped perpendicular to thecenterline of the boiler. Thus, as may be seen in FIG. 1, the piecesthat are preformed and illustrated in FIG. 3 are used as the center ofthe structure at the top. This allows for outer bays to be reduced inelevation relative to the boiler, thus reducing steel quantity andlateral loads.

The unique shop-fabricated grating panels preferably comprise twostandard-weight parallel beams 30, 31 with perpendicular channels 32across the beams to support the grating 33. This design essentially usesthe channels and beam top flanges as a horizontal Vierendeel truss.Superimposed on this truss are shop-welded grating bearing bars thatfunction as supplemental chord members to significantly increase therigidity of the panel. Through use of the grating members, diaphragmstiffness may satisfy AISC stability bracing requirements.

Channels 32 also facilitate framing around pipe and other commoditypenetrations and mitigate tripping hazards between adjacent panels byproviding means of attaching overhanging grating from adjacent panels.The grating floor panels, which generally span from column line girderto column line girder, are installed more quickly and safely becausethey include bearing-type connections (see FIG. 7). Heavily coped endssimulating precast double-T bearings in parking garages allow thestructure to be arranged with an eight and a half foot floor-to-floorheight without affecting headroom requirements.

While vertical Vierendeel trusses are common for prior art walkways, thepresent invention is actually utilizing them horizontally with gratingas a reinforcing structural component. Preferably, the frames are copedseated connections and the channels located with web horizontals suchthat they have sufficient flexibility to align with channels of adjacentpanels when brought together via the grating overlap. Preferably, thegrating panels are sized for standard trucks. Thus, when stacked, theweight approximately equals the maximum capacity of the trucks such thatthe trucks are not shipping “air.”

Similar to the process of creating the grating panels, partiallyshop-fabricated stair towers are fabricated to a maximum extent thatallows them to be shipped by rail or truck without special provisions.End frames include platform level grating and girts. Shop-assembledstair stringer frames also function as vertical bracing for open stairtowers and the upper two tiers of enclosed stair towers.

Shop-fabricated composite panels, such as floor panels 13 and checkeredplate burner panels 12, are created at the shop in order to avoidshipping beams that are loose with studs, decking, closure strips, etc.When these panels are assembled together to form a superstructure,concrete work, including rebar installation and concrete placement, maybe performed at ground level or, depending upon panel height in thebuilding, at the installed level. FIG. 4 illustrates examples of twotypes of checkered plate burner panels, 13 a, 13 b. FIG. 5 illustrates atop view of examples of floor panels 12 a, 12 b, while FIG. 7illustrates a bottom view of examples of floor panels 12 a, 12 b.

Generally, standard tripper floor framing is conventionally“stick-built” steel. Due to the elevation of at least 150 feet aboveground level or grade, the erection is generally time-consuming in craneusage as well as craft job hours. Thus, use of prefabricated panelsallows for three framing panels to be used per bay as opposed to severalhundered pieces (between 16 and 24 framing members, deck panels, edgeangles, studs, closure strips, etc) when done with the prior art“stick-built” method. Composite decking is shop-installed within thepanel periphery. Structural steel members are situated to function aspour stops. Panel bearing connections are used on primary steel beams.Reinforcing steel and concrete is placed at ground level or grade ratherthan more than 150 above grade. When the panels are used to formoperating decks for turbine buildings, wood panels are generally placedover the openings to serve as a temporary cover to satisfy safetyrequirements.

FIG. 5 illustrates checkered plate burner panels. The former approach ofdiscrete plates supported by framing members yielded many “levels” offraming before loads were delivered to the columns. For example,checkered plates spanned to angle stiffeners, stiffeners spanned tobeams, beams framed to girders, girders framed into transfer girders,and transfer girders framed into a major transfer girder before loadsfinally were transferred to a column.

Preferably, the checkered plate burner panels are sized (up to 12 feetby 60 feet maximum) to fit within a conventional oversized truck knownin the art. Indeed, preferably all of the preformed components are sizedto fit together on such a truck. The panels may be fabricated on a shopfloor upside-down with all downward fillet welds. Preferably, bearingconnections are used on primary steel beams to couple the panels to thesuperstructure.

Those skilled in the art will understand that many other components maybe included in designing and erecting a superstructure in accordancewith the present invention. For example, other components are often usedin designing and erecting a power generation plant that uses a boiler asdescribed herein but their description has been omitted for clarity.Preferably, most components used for designing and erecting asuperstructure in accordance with the present invention areprefabricated and sized to fit together on a truck or other form oftransportation. Additionally, those skilled in the art will understandthat there are numerous ways to connect and interlink the variouscomponents.

Thus, the present invention provides a concept that uses larger buildingcomponents, most of which have been wholly or partially preassembledoff-site. With the present invention, no horizontal bracing is requiredon the sides of the boiler. This lack of heavy diaphragm is feasible byhaving each column line act as a horizontal moment frame, including thecombined boiler/roof support at the top of the frame. HorizontalVierendeel trusses serve to introduce structural redundancy and functionas a light horizontal frame. Additionally, no east-west vertical bracingis required. This attribute avoids the numerous interferences andinefficient vertical bracing typically found with the large ductworklying parallel to the boiler. Use of shop-fabricated 10-to-12-foot-deepvertical trusses that function as horizontals is also beneficial. Thepresent invention also permits the extremely “commodity heavy” firsthundred feet of the superstructure to be installed in parallel with theboiler. Each soot blower bay (generally 30 feet by 40 feet) is simplyconstructed with four framing/floor panels and a total of only fourbolts.

Thus, the superstructure may be erected more quickly and efficiently ina cost-saving manner as opposed to the standard shipping of loosematerials to the drop site and then assembling all the loose materialsinto the superstructure.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

1. A method of erecting a structure for generating power with a boiler,the method comprising: erecting a primary framing system comprisingprefabricated, modular components including a combined prefabricatedprimary support and roof system and composite columns; and constructinga plurality of intermittent floor bays comprising prefabricated floorpanels made up of at least one of grating panels, checkered plates, andcomposite decks.
 2. A method in accordance with claim 1 wherein amajority of floor panel connections are with bearing connections
 3. Amethod in accordance with claim 1 wherein no diagonal horizontal bracingis used and no vertical bracing is used in two of four planes defined bythe structure.
 4. A method in accordance with claim 1 wherein the firsttwo steps are performed substantially simultaneously.
 5. A method inaccordance with claim 1 wherein components are sized to fit on vehiclesfor shipment.
 6. A method in accordance with claim 6 wherein the vehicleis a standard truck-trailer combination and the components are sized tofit on the trailer.
 7. A method in accordance with claim 1 wherein thetype of prefabricated panels may further comprise composite decking. 8.A structure comprising: a primary framing and roof support systemcomprising prefabricated roof truss sections, the roof truss sectionsbeing formed with horizontal panels consisting of interconnected beamsand vertical trusses interconnected with the beams of the panels; aplurality of intermittent floor bays within the primary framing and roofsupport system, the bays comprising floor support structures comprisingprefabricated panels of at least one of grating and decking coupled tobeams, the panels being coupled to beams of the primary framing and roofsystem; and a primary support structure comprising prefabricated panelsof checker plate panels coupled to the primary framing and roof supportsystem.
 9. A structure in accordance with claim 8 wherein a majority ofconnections between components are with bearing connections.
 10. Astructure in accordance with claim 8 wherein the primary support is fora boiler for generating power and the support comprises columnscomprising composite material.
 11. A structure in accordance with claim8 wherein no diagonal horizontal bracing is used and no vertical bracingis used in two of four planes defined by the structure.
 12. A structurein accordance with claim 8 wherein components are sized to fit onvehicles for shipment.
 13. A structure in accordance with claim 12wherein the vehicle is a standard truck-trailer combination and thecomponents are sized to fit on the trailer.
 14. A structure inaccordance with claim 8 wherein the types of prefabricated panels mayfurther comprise composite decking.
 15. A method of erecting a structurefor generating power with a boiler, the method comprising: erecting aprimary framing and roof support system comprising prefabricated rooftruss sections, the roof truss sections being formed with horizontalpanels consisting of interconnected beams and vertical trussesinterconnected with the beams of the panels; creating a plurality ofintermittent floor bays within the primary framing and roof supportsystem, the bays comprising floor support structures comprisingprefabricated panels of at least one of one of grating and deckingcoupled to beams, the panels being coupled to beams of the primaryframing and roof support system; creating a plurality of intermittentsupport bays within the primary framing and roof support system, thesupport bays comprising prefabricated panels of at least one of gratingand decking coupled to trusses, the modules being coupled to beams ofthe stair modules; and erecting a primary support structure comprisingprefabricated panels of checker plate panels coupled to the primaryframing and roof support system.
 16. A method in accordance with claim15 wherein a majority of floor panel connections are with bearingconnections
 17. A method in accordance with claim 15 wherein no diagonalhorizontal bracing is used and no vertical bracing is used in two offour planes defined by the structure.
 18. A method in accordance withclaim 15 wherein the first two steps are performed substantiallysimultaneously.
 19. A method in accordance with claim 15 whereincomponents are sized to fit on vehicles for shipment.
 20. A method inaccordance with claim 19 wherein the vehicle is a standard truck-trailercombination and the components are sized to fit on the trailer.
 21. Amethod in accordance with claim 15 wherein the type of prefabricatedpanels may further comprise composite decking.